High-level nickel plating



United States Patent 2,998,360 HIGH-LEVEL NICKEL PLATING Eugene N. Castellano, Seymour, Conn., assignor to The Seymour Manufacturing Company, Seymour, Conn.,

a corporation of Connecticut No Drawing. Filed 2, 1959, Ser. No. 796,252 6 Claims. (Cl. 204-49) This invention relates to foundation coatings for bright nickel plating processes, and more particularly the preliminary treatment of metallic surfaces by the electrodeposition of basic nickel foundation layers having a high degree of receptability.

Conventional procedures require the initial treatment of metals preparatory to the application of bright nickel surface layers with an adherent ductile base layer of nickel. Generally, prior procedures involving the application of the basic nickel layer require a special activating treatment to render the base nickel layer receptive to electrodeposition of the bright nickel surface layer. A

particular objective of the present invention is to provide I base nickel layers of inherent receptability to the outer bright nickel coating, thereby eliminating the necessity of a special activation step.

The base nickel. layers of the invention are electro lytically deposited from conventional plating baths and have the characteristics of ductility and smoothness'to an exceptional, degree. Compared with the available procedures for producing base nickel coatings, the presently described coatings have substantially higher leveling characteristics and are inherently activated during the depcsiticn processto provide high susceptibility for ,the subsequent application of bright nickel platings.

The invention involves the use of an additive comprising compounds of the following formula:

wherein R is a hydrocarbon radical, preferably an alkyl group, and X is an alkali or alkaline earth metal. Compounds of the indicated formula may be prepared by conventional procedures and are commercially available. The preferred compounds employed in the process of the invention are those wherein R is a methyl radical and X is magnesium. Other alkali and alkaline earth metal salts including alkoxy phenolic metal sulfates of the characterized formulation are appropriate and suitable in the practice of the present invention. The amount of the additive employed preferably lies within the range of from about 0.2 to 10 grams per liter based upon the composition of the electrolytic plating bath.

The major constituents of the plating bath may be the inorganic nickel sulfate and chloride salts. Nickel sulfate will, in practice, range from 180 to 400 grams/liter, and nickel chloride from 8 to 120 grams/liter of bath solution. This corresponds to a total available nickel content of about 40 to 120 grams/liter in solution. An average composition is 280 grams/liter of the nickel sulfate and 60 grams/liter of the nickel chloride, or a total of about 76 grams/ liter of available nickel.

Boric acid concentrations of from 8 to 50 grams/liter are desirable as a buffering agent, with a range of 30 to 50 being generally most suitable. Normally about 45 grams/liter of boric acid is considered to give optimum results. An anti-pitter or wetting agent comprising a sulfuric ester of a normal primary aliphatic alcohol having eight to eighteen carbon atoms in the molecule, such as sodium lauryl sulfate, is also desirably included in the 2,998,360 Patented Aug. 29, 1961 ICC 2 bath. Such anti-pitting agents are disclosed in the prior patent to Waite and Martin, No. 2,254,161. A small amount of this agent, on the order of 0.1 gram/liter, is suitable.

The pH of the bath may vary from a low of 3.0 to a high of 4.8 determined electrometrically, and the optimum range here is from 3.8 to 4.8. In general the process of the invention involves operating at bath temperatures ranging from about 35 to 60 C., with 50f to 55 C. being especially suitable in commercial practice. Cathode current densities of 25 to amperes per sq. ft. are practical in most cases and 50 to 55 amperes per sq. ft. is typical of good operating practice.

For purposes of illustration, the following specificexarnples of plating bath compositions within the scope of the invention are given:

Example 1 Nickel sulfate 300 grams/liter. Nickel chloride 60 grams/liter. Boric acid 45 grams/liter. Sodium lauryl sulfate 0.1 gram/liter. Methoxy phenol magnesium sulfate 0.6 gram/liter.

PH 4.0 (E). Temperature 55 C. I v Cathode current density 25 to 150 arnps./sq. ft.

Employing a bath of this composition, excellent elec trodeposits of high-level nickel are obtained over the entire range of cur-rent densities indicated. The addition of the activator has the elfectof rendering the electrodeposited nickel highly active and receptive to the sub sequent application of the bright nickel coating by conventional procedures.

Example 2 Nickel sulfate 300 grams/liter. Nickel chloride 60 grams/liter. Boric acid 45 grams/liter. Sodium lauryl sulfate 0.1 gram/liter. Ethoxy phenol potassium sulfate 2 grams/liter. pH 4.0 (E).

Temperature 55 C. Cathode current density 25 to .150 amps/sq. ft.

The nickel coating was applied in accordance with the procedures described above, using similar current densitim, and corresponding improvements are observed.

Example 3 Nickel sulfate 300 grams/liter. Nickel chloride 60 grams/liter. Boric acid 45 grams/liter. Sodium lauryl sulfate 0.1 gram/liter. Propoxy phenol calcium sulfate 1.5 grams/liter.

pH 4.0 (E).

Temperature 55 C.

Cathode current density 25 to 150 amps/sq. ft.

Example 4 Nickel sulfate 300 grams/liter.

Nickel chloride 60 grams/liter.

Boric acid 45 grams/liter.

Sodium lauryl sulfate 0.1 gram/liter.

Methoxy phenol sodium sulfate 3 grams/liter. pH 4.0 (E).

Temperature 55 C. Cathode current density 25 to 150 amps/sq. ft.

The procedures described in connection with Example 7' v 3 k 1 were followed in the application of this bath to iron or steel articles.

- Example 5 Nickel su1 f ate 300grams/liter. Nickel chloride---" 6O grams/liter Bo ic ac d f--.- -W-- 45 g m Sodium lauryl sulfate 0.1 gram/liter. Butoxy phenol magnesium sulfate 4 grams/ liter. P --e--.- Te pe atu e -----.---T Cathode current density 25 to 150 amps./ sq. ft.

R0 SOlX wherein R is a lower alkyl radical, and X is selected from the class consisting of alkali and alkaline earth metals.

2. A process for producing high-level base nickel coatings on metal which comprises electrodepositing a base nickel coating from an aqueous acidic solution of at least one nickel salt containing in solution from about 0.2 to about 10 grams per liter of an alkali metal lower alkoxy phenol sulfate.

3. A process for producing high-level base nickel coatings on metal which comprises electrodepositing a base nickel coating from an aqueous acidic solution of at least one nickel salt containing in solution from about 0.2 to about 10 grams per liter of an alkaline earth metal lower alkoxy phenol sulfate.

4. A process for producing high-level base nickel coatings on 'metal which comprises electrodepositing a base nickel coating from an aqueous acidic solution of at least one nickelsalt containing in solution from about 0.2 to about 10 grams per liter of an alkali metal methoxy phenol sulfate.

5, A process for producing high-level base nickel coatings on metal which comprises electrodepositing a base nickel coating from an aqueous acidic solution of at least one nickel salt containing in solution from about 0.2 to about 10 grams per liter of a methoxy phenol magnesium sulfate.

6. An aqueous electrolytic solution for producing inherent high adhesion for bright nickel platings comprising at least one nickel salt in an amount of from 8 to 400 grams per liter and from 0.2 to 10 grams per liter of an additive of the formula R0 SOLX References Cited in the file of this patent UNITED STATES PATENTS Flett Apr. 2, 1940 Haas et al. July 7, 1959 

1. A PROCESS FOR PRODUCING HIGH-LEVEL BASE NICKEL COATINGS ON METAL WHICH COMPRISES ELECTRODEPOSING A BASE NICKEL COATING FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT CONTAINING IN THE SOLUTION FROM ABOUT 0.2 TO ABOUT 10 GRAMS PER LITER OF AN ADDITIVE OF THE FORMULA 